Sedimentary Or Metamorphic (Base Substrate)

Muscovite Mica

KAl2(AlSi3O10)(OH)2

Quartz Vein in Matrix / Quartzite

Silicon Dioxide (SiO2) with host rock

Citrine (Heat-Treated Amethyst)

Silicon Dioxide (SiO2)

Quartzite

Metamorphic Quartzite (SiO2)

Greenstone or Chlorite Schist

Greenschist / Chlorite schist

Quartzite Cobble

Quartzite (SiO2 based)

Garnet Schist

Almandine-Muscovite Schist

Gravel Pebble (Likely Quartzite or Basalt)

Quartzite (or Macrocrystalline Quartz)

Muscovite Mica

Muscovite (KAl2(AlSi3O10)(OH)2)

Milky Quartz Pebble

Crystalline Silicon Dioxide (SiO2)

Citrine

Silicon Dioxide (SiO2) with iron impurities

Amethyst crystal

Silicon Dioxide (SiO2) with iron impurities

Mixed river gravel (alluvial conglomeratic sediment)

Polymictic alluvium; composition includes quartz, feldspar, chert, granite, basalt, and metamorphic rock fragments

Fuchsite

Cr-rich Muscovite (K(Al,Cr)2(AlSi3O10)(OH)2)

Sandstone (Ferruginous)

Arenite with Iron oxide staining (SiO2 with Fe2O3)

Gold

Native gold (Au)

Mica Schist

Mica Schist (primarily Muscovite or Biotite sheet silicates)

Red Quartzite

Metamorphic Quartzite (SiO2)

Fossilized Shark Tooth

Eocene Lamniformes (Mackerel Shark clade)

Quartzite river stone

Quartzite (SiO2)

Marble

Metamorphosed Limestone (principally CaCO3)

Labradorite

(Ca,Na)(Al,Si)4O8 (Plagioclase Feldspar)

Given the appearance, it's likely a fragment of an igneous or metamorphic rock composed of multiple minerals. Without specific diagnostic features, it's difficult to give a common name other than 'crystalline rock fragment'. If pressed to guess based on the granular, somewhat light and dark speckled appearance, it could be a fragment of granite or a related intrusive igneous rock.

As a rock fragment, it does not have a single scientific mineral name; rather, it's a piece of a rock which is a combination of minerals. If it were granite, its main mineral composition would be quartz (SiO2), feldspar (e.g., KAlSi3O8 - orthoclase, (Na,Ca)(Al,Si)4O8 - plagioclase), and mica (e.g., KAl2(AlSi3O10)(OH)2 - muscovite or K(Mg,Fe)3AlSi3O10(OH)2 - biotite), among others.

Dragon Blood Jasper (Epidote with Piedmontite or Quartz)

Epidote-rich Quartzite / SiO2 with (Ca2(Al2,Fe)(Si2O7)(SiO4)O(OH))

Botryoidal Chalcedony

Chalcedony (SiO2)

Aquamarine

Beryl (Be3Al2Si6O18 with iron impurities)

Milky quartz

Quartz (silicon dioxide, SiO₂)

Epidote

Epidote (Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH))

Fuchsite

Chromium-rich Muscovite (K(Al,Cr)2(AlSi3O10)(OH)2)

Gossan (Iron Hat) with Quartz and Chlorite

Limonite/Goethite-rich Gossan (FeO(OH)·nH2O) with inclusions of Quartz and Chlorite

Fuchsite

Chromian Muscovite (K(Al,Cr)2(AlSi3O10)(OH)2)

Common Gravel / Pebble

Lithified rock fragment / Detrital sediment

Pink Jade (Dyed Quartzite)

Silicon Dioxide (SiO2) - primarily Quartzite or Quartz

Magnesite or Howlite (dyed or naturally patterned)

Magnesium carbonate (MgCO3) or Calcium borosilicate hydroxide (Ca2B5SiO9(OH)5)

Quartz (Water-worn Pebbles)

Silicon Dioxide (SiO2)

Quartz

Silicon Dioxide (SiO₂)

Quartz with Schist Inclusion

Quartz (SiO2) with micaceous schist inclusions

Blue Quartzite

Quartzite (silicon dioxide, SiO2)

Epidotite (Unakite-related)

Epidote-rich rock

Painted River Rock

Anthropogenic-modified Siliciclastic Sedimentary Rock

Muscovite Mica

Muscovite, KAl2(AlSi3O10)(OH)2

Rhodonite

Rhodonite (Manganese silicate), (Mn,Fe,Mg,Ca)SiO3